Interacting drugs - summary

Difunisal + Acetaminophen                                                                                                        increased acetaminophen plasma levels. Acetoaminophen had no effect on difunisal plasma levels 

Anticoagulants oral                                                                                                                   incr co-admin of difunisal increase hypoprothrombin effects of anticoagulants. Monitor prothrombin times for several days after co-administration 

Hydrochlorthiazide                                                                                                              coadmin of difunisal resulted in increased plasma levels of hydrochlorothiazide 

Indomethicin                                                                                                                              admin of difunisal decreased renal clearance of and increased plasma levels of indomethicin. Combined use has also been to be associated with fatal GI haemorrhage

Sulindac                                                                                                                                 Admin of diflunisal resulted in lowering of the active sulindac sulfide metabolite.

long term treatment of mild to moderate pain.

Nausea, dyspepsia, GI pain, diarrhoea, vomiting, constipation, flatulance, peptic ulcer, GI bleeding/perforation, anorexia, eructation

. Headache,dizziness, somnolence, insomnia, vertigo, nervousness, hallucinations, confusion, disorientation, lightheadedness.

Fatigue/tirednessness edema,thrombosis. Dyspnea,muscle cramps, palpitations, syncope, chest pain.

Hypersens to the drug. Patients in whom acute asthmatic urticaria or rhinitis are precipitated by aspirin or other non-steroidal anti-rheumatic drugs.

Special precautions:

Platelet function and bleeding time are inhibited at higher doses. Perform opthalmological studies in patients who develop eye complaints during treatment.

Use in patients with compromised cardiac function. Possiblitity of association with Reye's syndrome cannot be excluded.

Indications:

long term treatment of mild to moderate pain.

Dosage:

Mild to moderate pain- Initially 1 g followed by 500 mg every 8 to 12 hours. A lower dosage may be appropiate- 500 mg initially,followed by 250 mg every 8 to 12 hours Osteoarthritis/rheumatoid arthritis- 500 mg to 1 g daily in 2 divided doses.

Do not exceed maintenance doses higher than 1.5 g daily.

1. May cause GI upset,may be taken with water,milk or meals.

2. Do not take aspirin or acetoaminophen with difunisal,except on doctors advise.

Pharmacology:

Difunisal is a salicylic acid derivative. It is a nonsteroidal peripherally acting nonnarcotic analgesic with anti-inflammatory and antipyretic properties. It differs from aspirin and metabolised to salicylic acid.Difunisal is a prostaglandin synthetase inhibitor.

Pharmacokinetics:

Difunisal is rapidly and completely absorbed following oral administration,peak plasma concentrations occur between 2 to 3 hours. The plasma half-life of difunisal is 8 to 12 hours.

Not significant

Pregnancy:

Safety for use during pregnancy has not been established. Use with caution only when potential benefits outweigh potential hazards.

Lactation:

Difunisal is excreted in breast milk . Because of the potential for adverse reactions in nursing infants, discontinue either nursing or the drug.